The conventional speed control device for the bicycle, in which the operating lever is rotatably supported to the fixing member to actuate the derailleur, is, in a well-known manner, provided with a positioning mechanism comprising (1) a positioning member having a plurality of engaging portions and mounted to one of the fixing member and the operating lever, (2) an engaging member mounted to the other of the fixing member and the operating lever and selectively engageable with one of the engaging portions, and (3) a spring biasing the engaging member toward the positioning member and maintaining engagement of the engaging member with the selected one of the engaging portions.
The spring has a spring force providing an engaging resistance sufficient to overcome a return spring at the derailleur in the condition in which the engaging member engages with one engaging portion, thereby maintaining the engaging condition and keeping the operating lever at one speed change stage. In other words, a reaction force of the spring acts on a torque of the operating lever to give thereto a rotational resistance, so that the operating lever, even when intended to turn, is maintained at a desired speed change stage because of overcoming the spring force.
Accordingly, when the operating lever is operated, the reaction force of the spring affects the torque of the operating lever, thereby allowing a cyclist to experience a clicking feel when operating the operating lever.
When the operating lever is operated, the engaging member disengages from the engaging portion and transfer to the adjacent one, with the torque changing as follows: The torque rises straight from a minimum to a maximum until the engaging member disengages from one engaging portion and falls to a medium value from the maximum value after the disengagement. Thereafter, the engaging member engages therewith to reduce the torque to a minimum value.
In the conventional speed control device, during the aforesaid switching of the engaging member, the reaction force of the spring biases the operating lever to the fixing member to apply a resistance against rotation of the lever, whereby the torque of the lever becomes larger than the medium value. At this time, the torque decreases from the maximum value to the minimum value through the aforesaid larger medium value, thereby reducing the rates of decrement from the maximum value to the medium value and to the minimum value.
As a result, a problem arises in that the cyclist, when operating the lever, experiences a poor clicking feel and cannot perform a brisk speed control operation.